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ashone15 (Chapter 15 ** )

Chapter Fifteen — Dangerous Beauty

A Short History of Nearly Everything – by Bill Bryson

Chapter 15 – Dangerous Beauty

  • Altogether there are about 10,000 visible volcanoes on Earth.  All but a few hundred are extinct.  But there is a second, less celebrated, type of volcano that doesn’t involve mountain building.  These are volcanoes so explosive that they burst open in a single mighty rupture, leaving behind a vast subsided pit, or caldera.  Yellowstone National Park contains a huge volcano of this type.
  • At some time in the past, Yellowstone must have blown up with a violence far beyond the scale of anything know to humans.  Yellowstone is a supervolcano.  It sits on top of an enormous hot spot, a reservoir of molten rock that rises from at least 125 miles down in the Earth.  The heat from the hot spot is what powers all of Yellowstone’s vents, geysers, hot springs, and popping mud pots.  Beneath the surface is a magma chamber 45 miles across.
  • The biggest volcanic blast in recent times was that of Krakatau in Indonesia in August of 1883.  This blast made a bang that reverberated around the world for nine days, and made water slosh as far away as the English Channel.  If you imagine the volume of ejected material from Krakatau as being the size of a golf ball, then the biggest of Yellowstone’s blasts would be the size of a 6-foot sphere.
  • Yellowstone is the site of an active supervolcano.  The eruptions of Yellowstone occur about every 600,000 years.  The last one was about 630,000 years ago.  Yellowstone, it appears, is due.
  • There are more geysers and hot springs in Yellowstone National Park than in all the rest of the world combined!
  • The last significant explosion in Yellowstone occurred in 1989 at Pork Chop Geyser.  It left a crater about 5 meters across – not huge by any means, but big enough if you happened to be standing nearby at the time.  The eruption happened without warning.
  • Organisms have now been discovered that thrive in very hot environments.  It had always been supposed that nothing could survive above temperatures of 122 degrees Fahrenheit, but Sulpholobus acidocaldarius and Thermophilus aquaticus bask in rank, acidic waters nearly twice that hot.  It was soon discovered that heat-resistant enzymes within these bacteria could be used to create a bit of chemical wizardry known as a polymerase chain reaction, which allows scientists to generate lots of DNA from very small amounts.  It is a kind of genetic photocopying.

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